Question
Download Solution PDFWhat value of a series resistor is required to limit the current through an LED to 20 mA with a forward voltage drop of 2.0 V, when connected to a 10-V supply?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
When LED conducts, it is replaced by its cut-in voltage with a limiting resistor connected in series with it.
\(R = {V_S - V_γ \over I}\)
where, VS = Source voltage
Vγ = Cut-in voltage
R = Limiting resistor
I = Current
Calculation:
Given, VS = 10V
Vγ = 2V
I = 20mA
\(R = {10 - 2 \over 0.02}\)
R = 400 Ω
Last updated on May 12, 2025
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